I think therefore that the freedom to choose, free will, is an assumption that underpins all discussion of moral choice. You must have free will to act morally. I think that from this fact you can get quite some way towards a system of ethics. Good, moral, actions would be those that uphold the free will of people thereby enabling further moral choices to be made. Bad actions would be those that take away or overrule someoneís free will and therefore take away their capacity to act in a moral fashion.
Also it is important that an action could have consequences, a real effect. If one were allowed infinite freedom to choose in a virtual world with no other users ones actions could never be said to be moral or immoral since there would be no possibility of having an effect on others. I suppose you could still have an effect on oneself, but what people do to themselves is often considered to be only their own business. Smart or stupid, but not moral or immoral.
If someone is not rational and able to make clearly thought out informed decisions about their actions there is a point where these factors mean that they are not morally responsible for their actions. One never can have every fact available to you at the instant you make a decision, since the possible eventual consequences of an action are almost infinite. But if you were completely ignorant of the consequences of your actions and could not reasonably be expected to find out before you act then you are not morally responsible for the consequences. One important thing in life is to find out what you could reasonably be expected to know about consequences so that you are able to make good decisions. Otherwise free will isnít terribly much use.
Finally I believe it is vital that people should be able to learn for themselves from their actions. Punishments that erase the memory of an offender, such as mindwipe in Babylon 5, or reprogram their response to events would seem to me more immoral than execution, since it would force people to go on with their lives with no possibility of finding for themselves the lesson their soul wanted to learn.